Field of the Invention and Related Art Statement
The present invention relates to a furnace for firing ceramic articles, and more specifically the invention relates to a continuous firing furnace which is used for sintering alumina ceramics and the like in a non-oxidizing atmosphere.
In the sintering of ceramic articles, firing has been conventionally carried out in a non-oxidizing atmosphere, for instance, a reducing atmosphere of hydrogen gas, a neutral atmosphere of nitrogen or argon gas, or a neutral atmosphere under vacuum so as to enhance the mechanical strength of the ceramic articles increasing the sintering density, improving the sinterability, and rendering the ceramic articles translucent. For example, U.S. Pat. No. 3,026,210 and U.S. Pat. No. 3,792,142 disclose the production of discharge lamp tube in which a green shaped body containing magnesium oxide is sintered in a non-oxidizing atmosphere to obtain translucent alumina ceramics.
Alumina ceramics and beryllia ceramics used for electronic circuit substrates and packages in semiconductor elements cermet and nitride ceramics used for machining tools have historically been sintered in non-oxidizing atmospheres.
Heretofore, there has been known a non-oxidizing atmosphere furnace for continuously firing ceramic articles. More particularly, this furnace has a interior which is divided by partition walls made of refractory bricks, thereby forming a plurality of zones to result in appropriate temperature zones in the furnace chamber, and a non-oxidizing gas such as hydrogen gas, nitrogen gas or the like is flows reverse to a direction in which ceramic articles to be treated are to be moved.